parse line number for branch points from PDB
more tests for branch coverage
fix: use branching instruction for getting source information,

more tests for switch,
samples: change switch variable to int (string is compiled to ifs)
refactor: remove tuple as return type (only Item1 is used)
remove unused variable
Merge branch 'line_num_for_branches' of https://github.com/molnargab/opencover into molnargab-line_num_for_branches
Ignore branches in methods with no sequence points
Merge branch 'molnargab-line_num_for_branches'